I tried to cram most of the details in the title. When this quite working, we pulled the cluster and pulled the cable from the tranny. Twisting one end turned the other end. definitely stiff but it did turn. So, we moved the car while looking down into the hole in the top of the tranny. It doesn't appear to be turning. We only moved a few feet but I would assume that would be enough to see it turn. Has anyone ever heard of an internal mechanical failure in the tranny that would cause this? The car drives and shifts normally.

 

Thanks,

Stephen

I think the problem is in the instrument cluster. Leave the cable attached to the instrument panel, use a drill the spin the other end of the cable and note if the speedometer moves.  

The gear that drives the cable inside the trans may have stripped. They're usually plastic and don't last forever.

Unfortunately, they're also a PITA to change on a Subaru.